And the S&P 500 index is up nearly 20% for the year, with the Dow up 17%.

Might it not be a good time to book a little profit?

Anyone who got in in January should have plenty to book after all. And not just in the U.S. In Europe the Stoxx 600 is up 11% and Japan’s Nikkei 225 is a bumper 38% to the good.

But even knowing all of the above there are those who think equity’s best days still lie ahead, and they seem to congregate in the U.S. investment banks.

Goldman Sachs’ chief global equity strategist Peter Oppenheimer, for example, reckons stocks’ bull run will continue as the market shifts into a new phase, driven by earnings and dividend growth, rather than valuation expansion.

He reiterated his bullish stance on global stocks Thursday, pointing to a ‘growth phase,’ which will produce more moderate returns with lower volatility.

“While valuation was a key factor behind the attractiveness of equities eighteen months ago, this is less the case now in our view. Strong equity returns over the past year have pushed up price to earnings ratios making valuation less of a clear driver for markets. We expect the baton to be passed to growth as the key driver moving forward,” Mr. Oppenheimer said.

He’s not alone either.

Bank of America Merrill Lynch is especially bullish on the prospects for the U.K. equity market, which it believes could grow its market capitalization by around 30% by 2015. The bank pointed to a pick-up in the pace of recovery in the country, coupled with ongoing loose monetary policy, and set a 2014 target of 7400 for the FTSE 100. This implies around 13% upside from current levels.

Bank of America recommends investors pile in to banks, retail and real estate stocks, which it sees as the best plays on a U.K. recovery. To play the global cycle, U.K. energy and travel & leisure sectors offer the greatest potential upside.